Over the years, there has been developed a substantial body of patent and other literature directed to the formation and properties of poly(aryl ethers) (hereinafter called "PAE"). Some of the earliest work such as by Bonner, U.S. Pat. No. 3,065,205, involves the electrophilic aromatic substitution (e.g. Friedel-Crafts catalyzed) reaction of aromatic diacylhalides with unsubstituted aromatic compounds such as diphenyl ether. The evolution of this class to a much broader range of PAE's was achieved by Johnson et al., Journal of Polymer Science, A-1, Vol. 5, 1967, pp. 2415-2427, Johnson et al., U.S. Pat. Nos. 4,108,837 and 4,175,175. Johnson et al., show that a very broad range of PAE can be formed by the nucleophilic aromatic substitution (condensation) reaction of an activated aromatic dihalide and an aromatic diol. By this method, Johnson et al. created a host of new PAE's including a broad class of poly(aryl ether ketones), hereinafter called "PAEK's".
PAE's presenting the greatest practical interest are those that contain the sulfone group. Thus, poly(aryl ether sulfones) (1) and (2) ##STR1## are commercially available tough thermoplastic materials. They possess a number of attractive features such as excellent high temperature resistance, good electrical properties, and very good hydrolytic stability. Polymer (1) is available from Imperial Chemical Industries, Ltd. under the trademark of Victrex Poly(ether sulfone). It is produced by the polycondensation of 4,4'-dihydroxydiphenyl sulfone with 4,4'-dichlorodiphenyl sulfone as described in, for example, Canadian Patent No. 847,963. The resin contains no aliphatic moieties and has a heat deflection temperature of approximately 210.degree. C. Material (2) is available from Amoco Performance Products, Inc., under the trademark of UDEL.RTM.. It has a heat deflection temperature of about 180.degree. C., and is made via the nucleophilic polycondensation of bisphenol-A di-sodium salt with 4,4'-dichlorodiphenyl sulfone, as described in U.S. Pat. No. 4,108,837.
Poly(aryl ether sulfones) are generally amorphous transparent materials displaying high heat distortion temperatures (HDT's). Thus HDT's well above 200.degree. C. have been observed for the polymers of formula (3) wherein Ar was (4), (5) or (6). ##STR2## The most important drawback of poly(aryl ether sulfones) resides in their relatively low chemical, solvent and stress-crack resistance.
In recent years, there has developed a growing interest in poly(aryl ether ketones) (PAEK's) as evidenced by Dahl, U.S. Pat. No. 3,953,400; Dahl et al., U.S. Pat. No. 3,956,240; Dahl, U.S. Pat. No. 4,247,682; Rose et al , U.S. Pat. No. 4,320,224; Maresca, U.S. Pat. No. 4,339,568; Atwood et al., Polymer, 1981, Vol. 22, August, pp. 1096-1103; Blundell et al., Polymer, 1983, Vol. 24, August, pp. 953-958; Atwood et al., Polymer Preprints, 20, No. 1, April 1979, pp. 191-194; and Rueda et al., Polymer Communications, 1983, Vol. 24, September, pp. 258-260. In the early to mid-1970's, Raychem Corporation commercially introduced a PAEK called STILAN.RTM., a polymer whose acronym is PEK, each ether and keto group being separated by 1,4-phenylene units. In 1978, Imperial Chemical Industries PLC (ICI) commercialized a PAEK under the trademark Victrex PEEK. As PAEK is the acronym of poly(aryl ether ketone), PEEK is the acronym of poly(ether ether ketone) in which the 1,4-phenylene units in the structure are assumed.
Thus, PAEKs are well known; they can be synthesized from a variety of starting materials; and they can be made with different melting temperatures and molecular weights. The PAEKs are crystalline, and as shown by the Dahl and Dahl et al. patents, supra, at sufficiently high molecular weights they can be tough, i.e., they exhibit high values (&gt;50 ft-lb/in.sup.2) in the tensile impact test (ASTM D-1822). They have potential for a wide variety of uses, but because of the significant cost to manufacture them, they are expensive polymers. Their favorable properties class them in the upper bracket of engineering polymers.
PAEKs may be produced by the Friedel-Crafts catalyzed reaction of aromatic diacylhalides with unsubstituted aromatic compounds such as diphenyl ether as described in, for example, U.S. Pat. No. 3,065,205. These processes are generally inexpensive processes; however, the polymers produced by these processes have been stated by Dahl et al., supra, to be brittle and thermally unstable. The Dahl patents, supra, allegedly depict more expensive processes for making superior PAEKs by Friedel-Crafts catalysis. In contrast, PAEKs such as PEEK made by nucleophilic aromatic substitution reactions are produced from expensive starting fluoro monomers and thus would be classed as expensive polymers.
PAEK's generally display low HDT's. Victrex PEEK, for example, has an HDT of about 140.degree.-160.degree. C., depending on the degree of crystallinity. Thus, while the overall properties of poly(aryl ether ketones) are outstanding, their low HDT's exclude them from some very important applications.
PAEK block copolymers have been described in U.S. Pat. Nos. 4,052,365 and 4,268,635. U.S. Pat. No. 4,052,365 describes random or block copolymers having repeating units of the structure --Ar--O--Ar--CO-- and --Ar--O--Ar--SO.sub.2 --. The patent states that these block copolymers are crystalline. U.S. Pat. No. 4,268,635 describes a process for preparing polymers containing --Ar--O--Ar--CO-- and --Ar--O--Ar--SO.sub.2 -- units which the patentee believes to contain block structures. The patent states that the polymers are crystalline and exhibit improved high temperature properties compared with totally random copolymers of similar composition.
U.S. Pat. No. 4,339,568 describes copolyethers based on hydroquinone, 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorobenzophenone prepared by the nucleophilic route. While most of the copolymers considered in the subject patent are random, Example 6 describes a block copolymer containing 20 mole percent of sulfone groups and 80 mole percent of ketone groups.
German Patent Application No. DE 3,602,090 claims a process for the preparation of block copolymers containing sulfone and ketone groups. The process uses the nucleophilic polycondensation route, and consists in the sequential additions of the aryl ether sulfone reactants, followed by the aryl ether ketone reactants.
The instant invention is directed to novel block poly(aryl ether)-poly(aryl ether ketone) copolymers. The distinguishing feature of the materials herein described is that they are based on a group of unique poly(aryl ether ketone) oligomers, prepared via the electrophilic Friedel-Crafts route. The starting materials of this invention are made via a process which is different than the one used in U.S. Pat. No. 4,339,568 and in German Patent Application No. DE 3,602,090. In addition, their structure is not the same as that of the oligomers employed in the aforementioned references (vide infra). In the preferred variant of our copolymerization process, the block integrity is preserved to a much higher extent because both blocks are preformed prior to coupling.